The present disclosure generally relates to voltage control. Specifically, the present disclosure relates to dynamic voltage control for a processing unit.
Electronic devices consume electric energy to generate desired output (i.e., light, heat, motion, etc.). Electric energy consumption is the actual energy demand made on an existing electricity supply. Voltage droop is an intentional loss in output voltage from a device as the output voltage drives a load. Employing droop in a voltage regulation circuit (e.g., voltage regulator) increases the headroom for load transients (i.e., short-lived bursts of energy in a system caused by a sudden change of state). The voltage regulator is designed to automatically maintain a constant voltage level (e.g., maintains a fixed voltage independent of the load resistance of the output current). Between the regulator output and the load is a series resistor. The resistance of the resistor is chosen such that at maximum output current, the output voltage at the load is the minimum acceptable. Conversely, when the output current is near and/or equal to zero, the voltage is near the maximum. This follows simply from Ohm's law as voltage equals current multiplied by resistance (V=I*R), and a calculation of power as voltage multiplied by current (W=V*I).
Voltage/current regulators can be made from a resistor in series with a diode and/or a series of diodes). Due to the logarithmic shape of diode V-I curves, the voltage across the diode changes only slightly due to changes in current drawn or changes in the input. Feedback voltage regulators operate by comparing the actual output voltage to some fixed reference voltage. Any difference is amplified and used to control the regulation element in such a way as to reduce the voltage error through a negative feedback control loop. If the output voltage is too low the regulation element is commanded to produce a higher output voltage—by dropping less of the input voltage (e.g., linear series regulators, buck switching regulators, etc.), or to draw input current for longer periods (e.g., boost-type switching regulators). If the output voltage is too high, the regulation element is commanded to produce a lower voltage.